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Abstract:
A Systematic Approach to Leptogenesis in the Standard Model. The mechanism
of Leptogenesis realized in the SM+3vR offers a convincing explanation for the observed
matter to anti-matter asymmetry of the universe. Although it is a genuine quantum effect,
its statistical aspects have been commonly treated in terms of cJassical equations. This
ambiguous interplay of particle physics and cosmology is critically reviewed leading to the
conclusion that in this conventional approach quantum statistical properties cannot be included
without violating the third Sakharov condition. A first principle approach based on
the CTP Kadanoff-Baym formalism of nonequilibrium QFT is required. A comprehensive
introduction to the necessary concepts is followed by an application to Leptogenesis in the
case of a hierarchical mass spectrum. We derive effective in-medium amplitudes of the
relevant processes and obtain quantum kinetic equations. They include both, CP-violating
decay and Δ,L = 2 lepton number violating scattering processes but are not affected by the
usually encountered double counting problem. In other words, quantum statistical effects
need not be neglected anymore. In addition, thermal corrections to the CP-violating parameter
arise. In agreement with previous findings, the structure of the thermal corrections
differs from earlier results obtained in the framework of thermal QFT.
